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Senate staffers are currently eyeing the second or third week in June for floor debate on the legislation.

After years of work, backers of the sweeping Cybersecurity Act of 2012 say they’re eager for Senate debate on the bill, but divisions over privacy and regulation show little sign of abating.

This was supposed to be the bill that got everyone on board. But its sponsors are back at the drawing board with Republicans, who say the bill would create too much government regulation; and with civil-liberties groups and some Democrats, who say the proposal could run roughshod over privacy laws.

The Cybersecurity Act was originally supposed to be up in the first working period of 2012. Senate staffers are currently eyeing the second or third week in June for floor debate on the legislation, which has the backing of the White House and Senate Democratic leaders.

The Senate Homeland Security and Governmental Affairs Committee has introduced broad cybersecurity legislation annually for the past several years, with little to show for it. Orchestrated by Majority Leader Harry Reid, D-Nev., a multi-committee, bipartisan working-group process was supposed to break the stalemate and deliver an omnibus bill.

That was the Cybersecurity Act of 2012, rolled out with much fanfare in February. Reid said he wanted it on the floor in the first working weeks of the session, but more than half a dozen GOP committee leaders criticized the measure and the process that produced it.

The act would increase government oversight of some private networks, such as electric grids, water systems, and transportation, that could be at risk from cyberattack. The Homeland Security Department would decide which businesses should be considered part of critical infrastructure.

Cyberthreats are expanding on a weekly basis, said Homeland Security Committee spokeswoman Leslie Phillips, who pointed to the recently discovered Flame virus as the latest example. “The threat is upon us,” she said. “Congress needs to pass legislation to strengthen the security of vulnerable networks now.”

A chief critic of the legislation, Senate Armed Services Committee ranking member John McCain, R-Ariz., said last week that he has made no headway in resolving disagreements over how far the government should go to protect private networks, and over which government agencies should take the lead.

McCain and other GOP committee leaders introduced their own cybersecurity bill, the Strengthening and Enhancing Cybersecurity by Using Research, Education, Information, and Technology Act, or the Secure IT Act. It would allow businesses to voluntarily share information about cyberthreats; limit liability for companies that take steps to protect their networks; restrict the type of information that can be shared, to protect privacy; and reform federal cybersecurity standards.

On the other side of the aisle, Sen. Ron Wyden, D-Ore., worries that proposals to encourage information-sharing on cyberthreats could undermine privacy and open the door to a “dystopian” system of tracking Internet traffic for future crimes. “These bills allow law-enforcement agencies to mine Internet users’ personal data for evidence of acts entirely unrelated to cybersecurity,” he said in a floor speech last week.

Wyden, who filibustered an online-piracy bill earlier this year, said he hasn’t decided how far he’ll go to protest the provisions in cybersecurity legislation, but his opposition gives a glimpse of the headache that Senate Democrats face as they try to gather votes.

The privacy flap is déjà vu for Homeland Security Chairman Joe Lieberman, I-Conn., and his cosponsors, who are meeting with civil-liberties groups that oppose the Cybersecurity Act on privacy grounds. A year ago, Lieberman and his allies revised another cybersecurity proposal in response to critics who said it could give the president the power to shut down the Internet.

Michelle Richardson, a lawyer with the American Civil Liberties Union, said her group is withholding judgment until it can work out potential changes with members of Congress, but she said she is hoping to see substantial revisions. A limited cybersecurity information-sharing bill, the Cyber Intelligence Sharing and Protection Act, passed the House with a bipartisan vote in April despite privacy concerns. But the White House threatened to veto it, and it is not expected to be considered in the Senate anytime soon.